Technical Speedometer not working after brake change - Mk2 2001 ELX speedgear

[masdon]

Hi all,

I've had a look around but don't see a direct answer to my issue so will try to solve here and document as I go.



I just got my Punto mk2 ELX speedgear 2001 back from its MOT ( 2 weeks in garage and £496 lighter in pocket).

Has had new pads/disks installed and the rear drum brake freed off and some welding.

Took it home, charged the battery for a day and today refitted and took it out for a test.

The speedometer is totally unresponsive, Below 0. This essentially renders the vehicle un-driveable.

Rev counter etc all working fine. All lights on dash come on and go off as should.

I think on ABS models there may be sensors on the brake which are responsible for speedometer readings but I'm not sure, and this could be post brake replacement paranoia ?

Could it be an issue with battery/earths?

Does anyone have any experience with this type of fault?

All advice appreciated

Cheers

 

[HgtBill]

Hi all,

I've had a look around but don't see a direct answer to my issue so will try to solve here and document as I go.



I just got my Punto mk2 ELX speedgear 2001 back from its MOT ( 2 weeks in garage and £496 lighter in pocket).

Has had new pads/disks installed and the rear drum brake freed off and some welding.

Took it home, charged the battery for a day and today refitted and took it out for a test.

The speedometer is totally unresponsive, Below 0. This essentially renders the vehicle un-driveable.

Rev counter etc all working fine. All lights on dash come on and go off as should.

I think on ABS models there may be sensors on the brake which are responsible for speedometer readings but I'm not sure, and this could be post brake replacement paranoia ?

Could it be an issue with battery/earths?

Does anyone have any experience with this type of fault?

All advice appreciated

Cheers

If its got ABS its fed from an ABS sensor ( on a HGT its the drivers front). If one was faulty you'd have an ABS fault light as well as a faulty speedo.

If its non ABS there's a speed sensor on the back of the gearbox.

Failing all that i'd check the fuse, especially as its had some welding done.

 

[masdon]

If its got ABS its fed from an ABS sensor ( on a HGT its the drivers front). If one was faulty you'd have an ABS fault light as well as a faulty speedo.

If its non ABS there's a speed sensor on the back of the gearbox.

Failing all that i'd check the fuse, especially as its had some welding done.

Thanks for that, great info.

Just had a check of the fuses, all the ones I checked were fine, including ABS fuse. I'm including an image of the fuse layout picture below for anyones future reference.

The car does have ABS, but what you said about the ABS light is pretty much what I was thinking. it comes on, goes off then comes back on for quick flash when started up. will obviously need to check whichever wheel the sensor is taking its reading from seen as brakes were changed.

It did also have a indicator bulb housing replaced, so from what I've read there have been issues with earths that also cause this issue, so will need to check that.

Then it will be on to the ECU.

Thanks again for the help.

 

[judderbar]

Thanks for that, great info.

Just had a check of the fuses, all the ones I checked were fine, including ABS fuse. I'm including an image of the fuse layout picture below for anyones future reference.

The car does have ABS, but what you said about the ABS light is pretty much what I was thinking. it comes on, goes off then comes back on for quick flash when started up. will obviously need to check whichever wheel the sensor is taking its reading from seen as brakes were changed.

It did also have a indicator bulb housing replaced, so from what I've read there have been issues with earths that also cause this issue, so will need to check that.

Then it will be on to the ECU.

Thanks again for the help.

Its a bit odd that the ABS unit does the self test and thinks all is well and then you get the flash of light as you start the car. On the cars from 2003 you can read the error codes for the ABS if you have all the plugs and software. It is a fiat specific. But fairly cheap to get. Multiecuscan software. and a specific plug/s from ebay. But i am not sure on your car you have the required obd2 plug? Multiecuscan website will most likely tell you what is supported for your car.

 

[masdon]

Thanks for that, I had thought something like that would be useful. From the multieciscan website I think what I have is listed "Fiat
Punto '99 1.2 16V" so I'm not sure it would work this time. Will look into it further.

Thanks again

 

[masdon]

Update:

Almost a year on and this issue is still not resolved. Its been a bit of an awkward one to figure out as you can imagine.

I used a generic ODB scanner to search for error codes and check speed sensors. This scan revealed no errors, the app also had function to read from speed sensor. The speed sensor appears to register and read the speed correctly via the app.

Does anyone know of any reason a speedometer would stop functioning when the sensors were still working/sending signal?

Could this be an EPAS or earth related issue?

any advice is appreciated

Thanks again

 

[judderbar]

my car is 2004 mk2b. When i turn the car on the dials on the speedo and the tachometer rise to reach the zero mark. If your speedo does not move like that it might just be the speedo itself that is broken.

 

[varesecrazy]

Definitely not a cable from the rear of gearbox?

 

[masdon]

my car is 2004 mk2b. When i turn the car on the dials on the speedo and the tachometer rise to reach the zero mark. If your speedo does not move like that it might just be the speedo itself that is broken.

That's definitely worth a look at, the tachometer etc are all working fine so my first assumptions (speed sensor / fuse) were based on the work which had been done prior to it failing. I will have a look into it and report back.

Thanks for your input, very much appreciated!

 

[masdon]

Definitely not a cable from the rear of gearbox?

I don't think so just based on the reading I'm getting from the sensor on the OBD scanner, but I will give a visual inspection and report back what I find.

Thanks again for responding, much appreciated.